The fact that in standard windings, the coils are placed into the slots of the laminated stacks makes this method not enough flexible for choosing any type of wire diameter, as the slots have a specific section, and the entrance to them is limited by the type of punch being used. It is widely commented in patent ES 531635 and although in that patent a winding system is also produced without iron, the differential issue from this, is the fact, that the wires are being placed fulfilling all the surrounding space of the electrical machine rotor.
One of the difficulties of manufacturing electrical machines with windings without slots is that this technology is not often being used as it is not easy to hold wires without any tooth to keep them.